This invention relates generally to organic Rankine cycle plants, and more particularly to methods and apparatus for controlling organic Rankine cycles using radial inflow turbines.
Rankine cycles use a working fluid in a closed cycle to gather heat from a heating source or a hot reservoir by generating a hot gaseous stream that expands through a turbine to generate power. The expanded stream is condensed in a condenser by rejecting the heat to a cold reservoir. The working fluid in a Rankine cycle follows a closed loop and is re-used constantly.
Superheated conditions at the inlet (front end) of the ORC turbine are required under all operation modes to avoid reduced turbine life expectancy or even immediate damage. In this regard, fixed speed turbines have only a low influence on vaporization and provide only a weak means for controls. Further, turbines devoid of variable inlet guide vanes are also devoid of means for controlling vaporization.
In view of the foregoing, it would be advantageous to provide efficient and cost effective methods and apparatus for controlling organic Rankine cycles using radial inflow turbines. The methods and apparatus should be capable of maintaining a desired superheating temperature at all operating conditions at the ORC turbine inlet without using sensors other than pressure and temperature sensors.